Received notice of a change to the service in my inbox today. Seems icky to me.
Devices in the network use Bluetooth to scan for nearby items. If other devices detect your items, they’ll securely send the locations where the items were detected to Find My Device. Your Android devices will do the same to help others find their offline items when detected nearby
Your devices’ locations will be encrypted using the PIN, pattern, or password for your Android devices. They can only be seen by you and those you share your devices with in Find My Device. They will not be visible to Google or used for other purposes.
ETA: here’s the link to opt out: opt out of the network
What I meant in opt-in is like make a switch somewhere in the first setup menu or make a pop-up telling about how useful it is and asking to enable it. And the problem is that this feature is not just opt-in but not even opt-out! You can’t disable it and therefore it’s straight up evil.